Montgomery County prosecutor Kelly Blackburn described the incident as a dynamic situation — Blackwelder, who was off-duty, shopping with his wife at Walmart on July 31, 2013, while Rios was alleged to have shoplifted from the store.

Police reports indicate Rios broke free from Walmart employees and ran from the store when Blackwelder saw Rios and chased him into a nearby wooded area. Blackwelder and Rios allegedly fought and at some point, Blackwelder discharged his Glock 22-caliber handgun, striking Rios in the back of the head.

They ran roughly 25-30 yards into the wooded area and no more than 1 minute 45 seconds went by between entering the woods and Blackwelder emerging alone.

According to defense claims, Rios had Blackwelder in a chokehold leading up to the shooting. The prosecution doesn’t see how the story adds up.

Blackburn said there is no way Rios could’ve been behind Blackwelder as the defense claims.

“When Jason Blackwelder told (Conroe police) that he had been choked by Russell Rios, they wanted to believe him,” Blackburn said. “He was their fellow officer. But from the very beginning, something was wrong. What they saw was Rios face-down with a bullet track up the back of his head and even with that, they wanted to believe him. But the more they tried to prove he wasn’t lying, the more it became evident he was. They weren’t seeing what he was saying.”

The prosecution argues Blackwelder carried the gun in the back of his pants without a holster and handled the weapon haphazardly when trying to apprehend Rios. Blackburn said Blackwelder went after Rios knowing the risk, but consciously disregarded it.

Defense attorney Greg Cagle, however, said the incredible irony in the case is the prosecution wanting jurors to believe Blackwelder shot Rios on accident and lied out of panic. But the defense maintains the shooting was done out of self-defense and Blackwelder’s legitimate fear for his own safety.

Cagle criticized the crime scene work and said evidence provided by the prosecution was “relatively soft science.” Cagle told the 12 jurors to consider the evidence, lack of evidence and that investigators were guessing about what happened.

“Police officers don’t decide to act. They have a sworn duty to act,” Cagle said. “If (Blackwelder) had ignored his oath and done nothing, we wouldn’t be here. But he didn’t ignore his oath. There was an extended struggle because Rios didn’t want to go to jail. He wanted to fight. The evidence is going to be that Rios assaulted Blackwelder and it’s a different situation when an officer is assaulted.”

Dr. Sparks Veasey III, Director of the Forensic Services Department of Montgomery County, performed the autopsy on Rios and was the only witness called to testify Monday.

Blackburn noted the two abrasions on Rios’ back, which Veasey referred to as tangential wounds, or wounds that don’t penetrate the skin.

Veasey said there was no way to determine whether Rios was standing or laying down at the time of the shooting, but the abrasions indicate the end of the gun barrel was in close proximity to his skin when it was fired.

Veasey said the bullet landed on a thick membrane between Rios’ brain and skull.

The trial resumes today at 9 a.m. in the 410th District Court at the Montgomery County Courthouse with Judge Frank Carmona presiding.